Condenser and method op making the same



. To all whom iamay concern);

NITED STATES.

PATENT OFFICE.

.mnn'r rnuns'sunr, or ms'r omen, NEW JERSEY, Assmnon 'ro wnsrm 111.110-

mc conm,'mcoarom-rnn,- ornnw roan, N. Yg, A conroaa'rron or NEW YORK.

cation for release nlcd'lune Be it knownthat I, ALBERT PRUnssmN, a citizen of the United States, residing at East Oran e, in the county of Essex and State of New ersey, have invented certain new and useful Improvements in --Condensers and Methods of Making the Same, of which the following is a full, clear, concise, and exact description.

This invention relates 'tocondensers and a method of making the same, its object be-" ing to provide an improved method of treating. condensers. to prevent a permanent change in their electrical constants as a result of normal temperature changes.

In composite circuits, which are used for the simultaneous sending. of telephone and telegraph messages, the requirements are such as to demand condensers which are very closely balanced in electrical constants with respect to each other. Also in. connection with various other electrical circuitsor net-.

works,-the1'e is a considerable demand for condensers, the electrical constants of which are necessarily held to" very close limits in order that the circuits may function properly. By following a procem of selection, it 15 pomible to obtain cups of-c'ondensers which initially meet t e various requirements, but experience has shown that such condensers,: even though made in the same manner and in factin the same lot, may vary consi'derably'from each othervafter being subjected to temperature changes to be exted under normal operating conditions. t is, therefore, the object of thepresent invention to provide a methodjof-treatment which, when a lied to the standard type of condensers, w1l insure that their electrical constants are not permanently afi'ected to an appreciable amount by normal changes in temperature.

The t'y e of condensers most commonly used in te ephone practice consists of alternate strips or layers of metal foil and insulating material, such as paper, rolled into a cylindrical or elliptical form. After this unit is wound, it is given a treatment to makeit impervious to moisture. Various methods are'employed to attain this result, one which has been found to vbe particularly satisfactory being described in detail in United States Patent 1,127,513, granted to oonnmrsnn m1) 1111153011 or MAKING THE sum.

specification of Beissued' Letters Patent. Reissued Nov, 29, 1921 no Drawing. Original pairwise, dated August 1:, 1918, Serial no. 183,131, filed .Tu1y'27, 1917. Appli- 14, 11520. Serial 1n. 388,995.

' the applicant on February 9, 1915. This 1t is dipped into an insulating compound and then placed in a metal. container, which 1s later completely filled with the insulating compound.

The additional treatment contemplated byth1 s invention consists in placing the treated unit in an oven, which is maintained at a temperature greater than the melting point of the impregnating wax and leavin it at this temperature for a given period 0 time, after which it is allowed to cool. Durin this treatment, any stresses, due to unequa "winding or unequal pressure during the shaping process, become equalized and the unit is free to take its natural shape, or, so to s eak, to take a permanent set, after .whic there will be no further tendency for changein shape, even though the-impregnating wax is in a fluid state. In the case ,of condensers which are impregnated with 'of-which is approximately 120 F., a satisparafiin wax, the solidifying-temperature factory treatment has been found to consist in placing the condensers in an upright position in an oven, the temperature of which is maintained at approximately 140 F., and leaving them, there for aperiod of from four to six hours after which they are allowed to cool. ,lilxtensive tests made on condensers sd treated indicate that no appreciable change ofa permanent nature will take place as a result of temperature changes such as would be experienced under normal operating condition.

What is claimed is:

1. The method of treating a condenser. impregnated in the presence of heat, which consists in applying pressure to the nn'preg nated condenser as it cools and then removing the pressure and-reheating the condenser to a temperature of not less than 120 F. fora period of not less than three hours pregnated condenser as it cools and then removing the pressure and reheating the con denser at a temperature equal to the melting point 'of the impregnating compound without pressure applied thereto for a time sufficient to permit itto expand to aishape approximately its shape prior to compres- S1011.

3. The method of treating a condenserimpregnated in the presence of heat, which consists in applying pressure to the impreg nated condenser as it cools and then removing the pressure and reheating the condenser without pressure applied thereto fora period of not less than three hours at a temperature equal to the melting point of the impregnating compound.

4. Themethodof treating a condenser impregnated in the presence of heat, which consists in applying pressure to the impregnated condenser as it cools and then removing the pressure and reheating the condenser" I without pressure applied thereto until the entire condenser has reached a temperature inginateria p 0 5. The method of treating a .COIldGIlSGPlID- pregnated in the presence of heat, which equal to the melting point of the impregnatconsists in giving the condenser a shape while cooling, and then reheating the condenser until it has reached a temperature equal to the melting point of the im reg nating material whereby it assumes a' ifi'en ent shape. I

6. The method of treating a. condenser having-la certain shape and impregnated in the presence of heat, which consists in applying pressure to the condenser as it cools to give it a difi'erent shape and then reheating the condenser without pressure applied thereto to permit" it to assume a shape ap' proximately like its first-mentioned certain shape. v 7. The method of treating a condenser impregnated in the presence of heat which consists in applying pressure to the condenser as it cools, removing the pressure, potting the condenser in a container having a crosssectional' dimension greater than the cross sectional dimension of= the compressed (IQI1"\50 denser, and reheating the potted condenser to permit it to assume a shape having a cross-sectional dimension greater than it had after being compressed.

8. The method of treating it rolled condenser impregnated in the presence of heat, consisting in applying pressure to the condenser as it cools to flatten the sides thereof, and then reheating the'condenser without pressure applied theretountil it reaches a temperature equal-to the melting "point of the impregnating material to permit it to assume again an approximate roll shape.

9.- The method of treating a condenser impregnatedin the presence of heat which con sists in applying pressure to the condenser as it cools to reduce its cross-sectional dimension, and then reheating the condenser without pressure applied thereto topermit it to expand. 10. The method of treating a condenser impregnated in the presence of heat, which consists in applying pressure to the con denser as it cools and then reheating the condenser without pressure applied thereto until it reaches a temperature equal to the melting point of the impregnating compound to permit the condenser to expand.

In witness. whereof, I hereunto subscribe my name this 7th day of June 1920., p

ALBERT PRUEssMANi 

